/usr/include/d2/4.6/std/atomics.d is in libphobos2-4.6-dev 0.29.1-4.6.3-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 | // Written in the D programming language.
/**
Implements processor dependent parts of the atomics library.
Macros:
WIKI = Phobos/Atomics
Copyright: Copyright Bartosz Milewski 2008 - 2009.
License: <a href="http://www.boost.org/LICENSE_1_0.txt">Boost License 1.0</a>.
Authors: Bartosz Milewski
Copyright Bartosz Milewski 2008 - 2009.
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
*/
version (D_InlineAsm_X86)
{
/**
Compare And Swap. The engine behind lock-free algorithms.
In one atomic operation, it tests the contents of $(D addr) and, if it's eqaul to $(D old), overwrites it with $(D new_val) and returns $(D true). Otherwise returns $(D false).
*/
bool CAS(uint * addr, uint old, uint new_val)
{
asm {
mov EDX, addr;
mov ECX, new_val;
mov EAX, old;
lock;
cmpxchg [EDX], ECX;
setz DL;
movzx EAX, DL;
}
}
/**
Stops the compiler from performing code motion across the barrier.
It's not a memory fence.
*/
void compiler_fence()
{
asm {
}
}
// The x86 implements processor-order memory model, so fences are not strictly necessary.
//
/** Memory read fence (includes compiler fence)
*/
void read_fence()
{
asm {
}
}
/** Memory write fence (includes compiler fence)
*/
void write_fence()
{
asm {
}
}
} // D_InlineAsm_X86
unittest
{
uint x = 1;
bool success = CAS(&x, 1, 2);
assert(success);
assert(x == 2);
success = CAS(&x, 1, 3);
assert(!success);
assert(x == 2);
}
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